SYNTHETIC JETS IN CROSS -FLOW. PART II: JETS FROM ORIFICES OF DIFFERENT GEOMETRY

The flow fields of synthetic jets in a cross -flow from orifices of different geometry are investigated. The g eometries include a straight, a tapered, a pitched and a cluster of nine orifices, all ha ving the same cross -sectional area through which the perturbation is discharged into t he cross -flow. The ‘strength’ of the jet from the tapered or ifice in comparison to that from the straight one is found to be only slightly enhanced. The flow field from the clu ster of orifices, when viewed a few equivalent diameters downstream, is similar to that from the single or ifice. However, the penetration is somewhat lower in the former case due to the increased mixing of the distributed jets with the cross -flow. The pen etr ation for the pitched configuration is the lowest , as expected. The jet trajec tories for the straight and pitched orifices are well represented by correlation equ ations available for steady jets -in -cross -flow. Distributions of streamwise velo city, vorticity as well as turbulence inte nsity are documented for various cases. In additio n, distributions of phase -averaged velocity and vorticity for the cylindrical and the clustered orifices are presented pr oviding an insight into the flow d ynamics.